1. Field of the Invention
The present invention relates to a semiconductor package, and more particularly, to a semiconductor package which is capable of electrically connecting to the outside without leads.
2. Description of the Related Art
Conventionally, semiconductor packages are formed by a process of loading a single or a plurality of semiconductor chips on a chip pad within a lead frame, protecting the interior by sealing the semiconductor chips with a sealant material, for example, epoxy molding compound (EMC), and then mounting the semiconductor chips on a printed circuit board (PCB). Recently, as electronic devices have increased in speed and capacity, and have become highly integrated, the power devices applied in automobiles, industrial equipment, and household appliances are faced with a requirement of becoming smaller and lighter. Simultaneously, since the electronic devices must achieve low heat emission and high reliability, a module package for a power supply, which has a plurality of semiconductor chips loaded on a single semiconductor package, is becoming more common.
FIG. 1A illustrates a cross-sectional view of a conventional semiconductor package 10. FIGS. 1B and 1C are each a perspective view and a side view, respectively, illustrating a conventional semiconductor package 10 to which leads are attached.
Referring to FIG. 1A, a semiconductor package 10 includes at least one power controlling semiconductor chip 3a indirectly attached to a substrate 1, and a low power semiconductor chip 3b which controls the power-controlling semiconductor chip 3b The wiring pattern 2 is a complex of stacked metal layers, including a copper wiring layer 2a formed on the surface of the substrate 1 and a nickel layer 2b covering the surface of the copper wiring layer 2a. 
Although the copper wiring layer 2a provides good electrical conductivity and thus is used as a base layer of the wiring pattern 2, it is easily oxidized even at low temperature, and therefore the surface of the copper wiring layer 2a is covered with a nickel layer 2b, which is an anti-oxidizing film. Since the nickel layer 2b does not have a good coating ability for the copper wiring layer 2a, and since the nickel layer 2b may also be oxidized, a gold layer 2c may be coated once more on the nickel layer 2b. The power controlling semiconductor chip 3a and the low power semiconductor chip 3b are each electrically connected to the wiring pattern 2 through wires 4a and 4b. 
The semiconductor chips 3a and 3b are connected to the outside through a lead 5. The lead 5 becomes a channel which connects the semiconductor chips 3a and 3b with the outside of the semiconductor package 10. That is, the semiconductor package 10 has the lead 5 protruding therefrom so as to transmit electrical signals to and from a circuit outside. The lead 5 affects the size of the semiconductor package 10, and when mounted on an external circuit board, a bend may occur in the lead 5.
Referring to FIGS. 1B and 1C, a conventional semiconductor package 10 to which a plurality of leads 5 are attached is illustrated. The conventional semiconductor package 10 is a semiconductor package disclosed in U.S. Design Pat. No. 505,399. When the semiconductor package 10 according to the prior art is mounted on an external circuit board, the distance of insulation d between external leads 5 protruding from the semiconductor package 10 may not be stably maintained.
Therefore, there is a need to implement a semiconductor package which can overcome the lead bending, and can be stably mounted on an external circuit board.